5. Description of the parameters in PION parameter files

divide up parameters by topic and describe them in tables.

5.1. Stellar Winds

Stellar winds in PION are implemented in 3 modules: a constant wind, an evolving wind, and a latitude-dependent wind. The parameter file for a constant wind has a number of parameters that should be set, quoted below with the expected units. They are stored in these units in the SWP struct of type stellarwind_params.

Parameter Description Units/values
WIND_[i]_pos[n] Star position \(n\in[0,1,2]\) cm
WIND_[i]_radius Radius of wind injection region cm
WIND_[i]_type [Constant, evolving, latitude dependent] [0,1,2]
WIND_[i]_mdot Mass-loss rate from star (dot{M}) \(\mathrm{M_{\odot}\,yr}^{-1}\)
WIND_[i]_vinf Terminal velocity of wind \(\mathrm{km\,s}^{-1}\)
WIND_[i]_vrot Equatorial rotation velocity \(\mathrm{km\,s}^{-1}\)
WIND_[i]_temp Effective Temperature of star, \(T_\mathrm{eff}\) K
WIND_[i]_Rstr Radius of star cm
WIND_[i]_Bstr Strength of surface magnetic field Gauss
WIND_[i]_TR[n] Value of tracer \(n\) in wind Usually \(\in [0,1]\)
WIND_[i]_evofile Text file with data for evolving wind Default is NOFILE
WIND_[i]_t_offset offset of sim time from evolution time Default is 0.0
WIND_[i]_t_scalefac scaling simulation time to evolution time Default is 1.0
WIND_[i]_updatefreq How often to update the wind seconds
WIND_[i]_enhance_mdot ad-hoc flag to increase \(\dot{M}\) Default is 0

For constant winds, these data are stored in the global struct SWP, defined in pion/source/constants.h, using these units. In simulation snapshots they also have the same units. The evolving wind file should have all units in CGS.